"Microsoft announced that Office 365™ now has over 85 million monthly active users during their earnings call on Oct. 20. This is up more than 40% year over year..."

We all know that the cloud is by far the one obvious benefit of companies moving their mail off-prem (leading to Office 365's success), but what have been the other big drivers here in its rise? Good marketing? Better product? Why do you personally like...or dislike...Office 365 as an end-user or admin?

For us, the driver was the complexity and cost of migrating from Exchange 2003 to a newer version. MS appear to have made Exchange much more enterprise-y, with it really being aimed at organisations with teams of people dealing with AD, teams dealing with mail, teams dealing with everything. Our Exchange team was mostly me. Our AD team is anyone in the (small) department.

Managing and protecting that looked like a nightmare, and that's before considering hardware costs. So O365 was a good choice for us.

Things we like: easier configuration of mobile devices, O365 portal a major improvement on our old OWA, shared mailboxes are proving very useful.

Things we (and our users) like less: Outlook not passing through the credentials of the logged in user, which causes confusion when passwords are changed (even after this has been explained). More convoluted process to configure new users (not as bad as it first seems, but slows us down a bit).